border-1px($color)
	position: relative
	&:after
		display: block
		position: absolute
		left: 0
		bottom: 0
		width: 100%
		border-top: 1px solid $color
		content: ' '

border-none()
	&:after
		display: none
	
bg-image($url)
	background-image:url($url + "@2x.png")
	@media (-webkit-min-device-pixel-ratio: 3),(min-device-pixel-ratio: 3)
		background-image:url($url + "@3x.png")